Adhesive film, adhesive film with support sheet, and structure

Abstract

An adhesive film containing a thermally conductive filler (A) having a two-dimensional crystal structure, an epoxy component (B), a curing agent (C), and a binder polymer (D), the adhesive film 1 being such that at least one of the epoxy component (B) and the curing agent (C) has a conjugated mesogenic skeleton. This adhesive film 1 exhibits exceptional thermal conductivity.

Description

[Technical Field]

[0001] The present invention relates to an adhesive film having excellent thermal conductivity and a method for producing the same, an adhesive film with a support sheet, and a structure and a method for producing the same. [Background technology]

[0002] Conventionally, heat dissipation members having thermal conductivity have been used to dissipate generated heat in electronic devices such as semiconductor devices including thermoelectric conversion devices, photoelectric conversion devices, and large-scale integrated circuits. For example, methods for efficiently dissipating heat generated from a semiconductor device to the outside have included using a liquid thermally conductive adhesive with high thermal conductivity that is highly filled with inorganic filler to bond the semiconductor device to a heat sink, or providing a sheet-like heat dissipation member (film, sheet) with excellent thermal conductivity between the semiconductor device and the heat sink.

[0003] The above-mentioned film or sheet is produced by applying a coating liquid of a heat dissipation material containing an adhesive resin, an inorganic filler, a curing agent, and a solvent to a release sheet or a substrate and drying it, as exemplified in Patent Document 1. Examples of the inorganic filler that can be used include silica, alumina, glass, and titanium oxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-67713 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional films and sheets containing inorganic fillers have not always achieved the desired thermal conductivity. Therefore, there is a demand for films and sheets with even better thermal conductivity. Here, when conventional films and sheets containing inorganic fillers are heavily loaded with inorganic fillers to achieve high thermal conductivity, they become mechanically brittle, their flexibility decreases, and process defects such as the generation of broken pieces during use may occur. Furthermore, the increased surface roughness of the sheet-like heat dissipating member makes it difficult to develop tack, making it difficult to obtain temporary adhesion when attached to an adherend, or making it more likely to entrap air when attaching the sheet-like heat dissipating member to an adherend, resulting in the formation of many voids at the adhesive interface between the sheet-like heat dissipating member and the adherend. Furthermore, high loading results in many interfaces between the inorganic filler and other organic material components such as adhesive resins within the sheet-like heat dissipating member. Therefore, if peeling occurs at these interfaces, many voids may form within the sheet-like heat dissipating member, resulting in reduced thermal conductivity.

[0006] Recently, in a wide range of fields, including electronics and fuel cells, composite resin materials incorporating graphene, which has excellent electrical, thermal, and optical properties, have been proposed as a replacement for conventional inorganic fillers. When graphene is dispersed in a resin and used as a composite resin material, it is necessary to uniformly disperse the graphene in the resin. However, due to the graphene's cohesion and affinity with the resin, it is difficult to uniformly disperse graphene in the resin. Insufficient dispersion can result in inconsistent thermal conductivity, and adhesive films in which graphene is dispersed in a binder resin as a heat-dissipating filler have not yet been put to practical use.

[0007] The present invention has been made in consideration of the above-described circumstances, and aims to provide an adhesive film having excellent thermal conductivity and a method for manufacturing the same, an adhesive film with a support sheet, and a structure and a method for manufacturing the same. [Means for solving the problem]

[0008] In order to achieve the above object, first, the present invention provides an adhesive film containing a thermally conductive filler (A) having a two-dimensional crystal structure, an epoxy component (B), a curing agent (C), and a binder polymer (D), wherein at least one of the epoxy component (B) and the curing agent (C) has a π-conjugated mesogenic skeleton (Invention 1).

[0009] Secondly, the present invention provides an adhesive film containing a thermally conductive filler (A) having a two-dimensional crystal structure, an epoxy component (B) having a π-conjugated mesogen skeleton, and a binder polymer (D) (Invention 2).

[0010] In the adhesive films according to the above inventions (Inventions 1 and 2), the thermally conductive fillers (A) with many π electrons tend to come into close proximity with each other due to their interactions, and their shape gives them a large specific surface area, making them more likely to come into contact with each other. Furthermore, the interaction between the π electrons of the thermally conductive filler (A) and the π electrons of the epoxy component (B) and / or curing agent (C) allows the thermally conductive filler (A) to disperse well in the adhesive resin composition and, consequently, in the adhesive film, suppressing aggregation and segregation. These actions facilitate the formation of thermal conduction paths through the thermally conductive filler (A) in the adhesive film, thereby exhibiting excellent thermal conductivity.

[0011] In the above inventions (Inventions 1 and 2), the content of the thermally conductive filler (A) having a two-dimensional crystal structure is preferably 5% by mass or more and 60% by mass or less (Invention 3).

[0012] In the above inventions (Inventions 1 to 3), the thermally conductive filler (A) having a two-dimensional crystal structure is preferably graphene (Invention 4).

[0013] In the above inventions (Inventions 1 to 4), the wavenumber in the absorption spectrum obtained by Raman measurement is 1570 cm -1 The peak value of the G band absorption intensity (I G ) for the wavenumber 1250 cm -1 The peak value of the D band absorption intensity (ID ) is preferably 0.5 or less (Invention 5).

[0014] In the above inventions (Inventions 1 to 5), it is preferable that the epoxy component (B) has a naphthalene skeleton or a biphenyl skeleton as the π-conjugated mesogenic skeleton (Invention 6).

[0015] In the above inventions (Inventions 1 to 6), the curing agent (C) is preferably a phenol-based curing agent having a biphenyl skeleton as the π-conjugated mesogenic skeleton (Invention 7).

[0016] In the above inventions (inventions 1 to 7), it is preferable that the product is obtained by heat pressing (invention 8).

[0017] Thirdly, the present invention provides a method for producing an adhesive film, which comprises mixing a thermally conductive filler (A) having a two-dimensional crystal structure with a binder polymer (D) in a solvent, and then further mixing an epoxy component (B), at least one of which has a π-conjugated mesogenic skeleton, and a curing agent (C) to obtain an adhesive resin composition, and then forming the obtained adhesive resin composition into a film (Invention 9).

[0018] Fourthly, the present invention provides a method for producing an adhesive film, characterized by mixing a thermally conductive filler (A) having a two-dimensional crystal structure with a binder polymer (D) in a solvent, and then further mixing an epoxy component (B) having a π-conjugated mesogen skeleton to obtain an adhesive resin composition, and then forming the obtained adhesive resin composition into a film (Invention 10).

[0019] In the above inventions (Inventions 9 and 10), it is preferable that the adhesive resin composition is formed into a film and then further subjected to heat pressing (Invention 11).

[0020] Sixthly, the present invention provides an adhesive film with a support sheet, comprising the adhesive film (Inventions 1 to 8) and a support sheet laminated on at least one side of the adhesive film (Invention 12).

[0021] Seventhly, the present invention provides a structure (Invention 13) in which at least a part of a first member and at least a part of a second member are bonded together via a cured product of the adhesive film (Inventions 1 to 8).

[0022] In the above invention (Invention 13), it is preferable that the first member is a semiconductor element, and the second member is a semiconductor element or a substrate (Invention 14).

[0023] Eighth, the present invention provides a method for producing a structure in which at least a part of a first member and at least a part of a second member are bonded via the cured body by bonding at least a part of a first member to at least a part of a second member via the adhesive film (Inventions 1 to 8), and then heat-treating the adhesive film to form a cured body (Invention 15). [Effects of the Invention]

[0024] The adhesive film, adhesive film with support sheet, and structure according to the present invention have excellent thermal conductivity. Furthermore, the method for producing an adhesive film according to the present invention makes it possible to produce an adhesive film with excellent thermal conductivity. Furthermore, the method for producing a structure according to the present invention makes it possible to produce a structure with excellent thermal conductivity. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view of an adhesive film with a support sheet according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a structure according to one embodiment of the present invention. [Figure 3] 1 is a graph showing the results of Raman measurement of the adhesive film of Example 1. [Figure 4]1 is a graph showing the results of Raman measurement of the adhesive film of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described. [Adhesive film] The adhesive film according to this embodiment either contains, first, a thermally conductive filler (A) having a two-dimensional crystal structure, an epoxy component (B), a curing agent (C), and a binder polymer (D), wherein at least one of the epoxy component (B) and the curing agent (C) has a π-conjugated mesogenic skeleton, or, second, contains a thermally conductive filler (A) having a two-dimensional crystal structure, an epoxy component (B) having a π-conjugated mesogenic skeleton, and a binder polymer (D). Note that a composition containing the above components may be referred to hereinafter as "adhesive resin composition R."

[0027] Thermally conductive fillers (A) with a two-dimensional crystal structure have many strong double bonds, which allow them to exhibit excellent thermal conductivity through phonons. Furthermore, thermally conductive fillers (A) with many double bonds have many π electrons. Due to the interaction of these π electrons, the thermally conductive fillers (A) tend to come into close proximity with each other, and furthermore, due to their shape and large specific surface area, the thermally conductive fillers (A) tend to come into contact with each other. This facilitates the formation of heat conduction paths within the adhesive film, allowing for excellent thermal conductivity even with a small amount added. Therefore, by using the thermally conductive filler (A), excellent thermal conductivity can be obtained without a high loading of the thermally conductive filler (A) in the adhesive film.

[0028] Furthermore, the thermally conductive filler (A) having a two-dimensional crystal structure is flexible due to its shape. Therefore, an adhesive film containing the thermally conductive filler (A) has excellent flexibility. Furthermore, since there is no need to highly fill the thermally conductive filler (A) as described above, the adhesive film is prevented from becoming mechanically brittle and exhibits excellent mechanical toughness.

[0029] When an adhesive film has excellent flexibility, it is less likely to entrap air when applied to an adherend, preventing voids from forming at the interface between the adhesive film and the adherend, and increasing the contact area between the adhesive film and the adherend. That is, it is possible to prevent voids at the interface between the adhesive film and the adherend from increasing thermal resistance, thereby improving thermal conductivity between the adhesive film and the adherend. Furthermore, preventing the adhesive film from becoming mechanically brittle as described above reduces the probability of process defects, such as the generation of broken debris, occurring during use.

[0030] While the thermally conductive filler (A) having a two-dimensional crystal structure has excellent thermal conductivity as described above, it also has a very stable chemical structure and is non-polar due to its symmetry, making it difficult to disperse in solvents or polymeric materials. In this embodiment, the epoxy component (B) and / or the curing agent (C) have a π-conjugated mesogenic skeleton, which has many π-electrons. As described above, the thermally conductive filler (A) also has many π-electrons. Due to the interaction between the π-electrons of the thermally conductive filler (A) and the π-electrons of the epoxy component (B) and / or the curing agent (C), the thermally conductive filler (A) is well dispersed in the adhesive resin composition R and, by extension, in the adhesive film, and aggregation and segregation are suppressed. When the thermally conductive filler (A) is well dispersed, the thermal conduction paths are more easily formed, resulting in even better thermal conductivity due to the thermally conductive filler (A).

[0031] Here, as mentioned above, when conventional inorganic fillers are heavily loaded to obtain the desired thermal conductivity, the surface roughness of the adhesive film increases, making it difficult to develop tackiness, and there are also problems such as a decrease in adhesive properties and even a decrease in mechanical strength. On the other hand, the thermally conductive filler (A) in this embodiment can obtain high thermal conductivity without being heavily loaded as described above, so the surface roughness of the adhesive film can be reduced, thereby exhibiting suitable adhesive strength (temporary adhesiveness). Furthermore, even after curing, it exhibits excellent adhesive properties, particularly excellent shear adhesive strength, resulting in high adhesive reliability.

[0032] Furthermore, conventional liquid thermally conductive adhesives highly filled with inorganic fillers lack thickness stability, and when used as adhesives in semiconductor devices and the like, the device performance does not manifest as designed, or the characteristics vary from device to device, making it difficult to obtain a product of stable quality. The adhesive film of this embodiment contains the binder polymer (D), which imparts film-forming properties, resulting in a film shape with high thickness accuracy and excellent stability of properties. Therefore, by using the adhesive film of this embodiment in semiconductor devices and the like, it is possible to produce products of stable quality.

[0033] 1. Each ingredient (1) Thermally conductive filler (A) The adhesive film according to this embodiment contains a thermally conductive filler (A) having a two-dimensional crystal structure. Here, a "thermally conductive filler having a two-dimensional crystal structure" refers to a filler that has a structural periodicity in two dimensions and has a layer with a thickness of a single atom, and that is composed of only that layer, or that has layers stacked by van der Waals forces in a number of layers from two to several hundred. Experimentally, in wide-angle X-ray diffraction (WAXD) measurements of such a "thermally conductive filler having a two-dimensional crystal structure," a clear crystalline peak is obtained from the periodic structure. Furthermore, in the case of a multi-layer structure, a crystalline peak attributable to the periodic structure in the thickness direction of the layer is also obtained.

[0034] For example, when the "thermally conductive filler (A) having a two-dimensional crystal structure" is graphene, when the adhesive film according to this embodiment is measured by X-ray diffraction using a CuKα radiation source (wavelength 0.15418 nm), peaks are preferably detected at 2θ positions of 26.6° and 42.4°. The diffraction peaks at 2θ positions of 26.6° and 42.4° are interlayer and intraplane crystalline peaks of graphene, and the detection of peaks at such positions indicates that the graphene has a crystalline structure.

[0035] Furthermore, when the "thermally conductive filler (A) having a two-dimensional crystal structure" is monolayer boron nitride, when the adhesive film according to this embodiment is measured by X-ray diffraction using a CuKα radiation source (wavelength 0.15418 nm), diffraction peaks are preferably detected at 2θ of 26.8° and 41.6°. The peaks at 2θ of 26.8° and 41.6° are interlayer and intraplane crystalline peaks of boron nitride, and the detection of peaks at such positions indicates that the boron nitride has a crystalline structure. The measurement can be carried out, for example, using a wide-angle X-ray diffraction measurement diffractometer (Rigaku Corporation, product name "SmartLab") or the like.

[0036] Examples of the thermally conductive filler (A) having a two-dimensional crystal structure include graphene and single-layer boron nitride. One type may be used alone, or two or more types may be used in combination. They may also be used in combination with other thermally conductive fillers such as alumina particles or aluminum nitride particles. Graphene in this specification also includes graphene produced by thinly exfoliating (cleaving) graphite. However, graphite itself does not fit the definition of a "thermally conductive filler having a two-dimensional crystal structure" described above, and therefore does not fall under the category of a "thermally conductive filler having a two-dimensional crystal structure" in this specification.

[0037] Graphene obtained by physically cleaving graphite is preferred, as it has a good two-dimensional crystal structure. On the other hand, reduced graphene oxide (RGO), which is produced by cleaving oxidized graphite to form a single layer (graphene oxide) and then reducing it, has low crystallinity and is therefore unsuitable for this embodiment.

[0038] The thermally conductive filler (A) having a two-dimensional crystal structure, such as the above-mentioned graphene and single-layer boron nitride, exhibits excellent thermal conductivity, as described above.

[0039] The graphene and single-layer boron nitride preferably have a thickness that is 1 / 10 or less of the shortest length in a planar view.

[0040] The average particle size of the thermally conductive filler (A) having a two-dimensional crystal structure is preferably 0.5 μm or more, more preferably 1.0 μm or more, particularly preferably 3.0 μm or more, and even more preferably 5.0 μm or more. This allows the characteristics of the two-dimensional structure to function, facilitating contact between the thermally conductive fillers (A) and the formation of thermal conduction paths, resulting in an adhesive film with excellent thermal conductivity. Furthermore, the average particle size of the thermally conductive filler (A) is preferably 30 μm or less, particularly preferably 20 μm or less, and even more preferably 15 μm or less. This maintains the dispersed state in other materials such as the solvent and binder polymer (D), preventing segregation from preventing the formation of thermal conduction paths, resulting in an adhesive film with excellent thermal conductivity.

[0041] The thickness of the thermally conductive filler (A) is preferably 500 nm or less, more preferably 300 nm or less, particularly preferably 200 nm or less, and even more preferably 100 nm or less. This allows the flexibility of the resulting adhesive film to be maintained well. On the other hand, the lower limit of the thickness of the thermally conductive filler (A) is not particularly limited, but is usually 0.7 nm or more, and from the viewpoint of thermal conductivity, it is preferably 5.0 nm or more, particularly preferably 10 nm or more, and even more preferably 15 nm or more.

[0042] The content of the thermally conductive filler (A) in the adhesive film (adhesive resin composition R) is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, and even more preferably 20% by mass or more. When the lower limit of the content of the thermally conductive filler (A) is as described above, the thermally conductive fillers (A) are more likely to come into contact with each other, making it easier to form thermal conduction paths, and the resulting adhesive film has better thermal conductivity.

[0043] Furthermore, the content of the thermally conductive filler (A) in the adhesive film (adhesive resin composition R) is preferably 60% by mass or less, more preferably 55% by mass or less, particularly preferably 50% by mass or less, and even more preferably 40% by mass or less. By setting the upper limit of the content of the thermally conductive filler (A) as described above, the resulting adhesive film is prevented from becoming mechanically brittle, and has better flexibility. In this embodiment, by using the thermally conductive filler (A), the desired thermal conductivity can be obtained even with a relatively small content as described above.

[0044] (2) Epoxy component (B) The epoxy component (B) in this embodiment may be one that requires a curing agent (C), or may be one that cures without the need for a curing agent (C). In the case of an epoxy component (B) that requires a curing agent (C), at least one of the epoxy component (B) and the curing agent (C) has a π-conjugated mesogenic skeleton. In the case where the epoxy component (B) does not require a curing agent (C) and the adhesive film does not contain a curing agent (C), the epoxy component (B) has a π-conjugated mesogenic skeleton. Note that both the epoxy component (B) and the curing agent (C) may have a π-conjugated mesogenic skeleton.

[0045] As the epoxy component (B) having a π-conjugated mesogen skeleton, an epoxy resin having a naphthalene skeleton, an epoxy resin having a biphenyl skeleton, or an epoxy resin having an anthracene skeleton is preferred, and an epoxy resin having a naphthalene skeleton or an epoxy resin having a biphenyl skeleton is particularly preferred. These may be used alone or in combination of two or more. For convenience, the term "epoxy resin" in this specification also includes unpolymerized or low-molecular-weight epoxy compounds.

[0046] Preferred examples of epoxy resins having a naphthalene skeleton include those represented by the following formula:

[0047] [ka] (wherein n is an integer of 0 or more).

[0048] [ka]

[0049] Preferred examples of epoxy resins having a biphenyl skeleton include those represented by the following formula:

[0050] [ka] (wherein n is an integer of 0 or more). [ka] [ka]

[0051] Preferred examples of epoxy resins having an anthracene skeleton include those represented by the following formula:

[0052] [ka]

[0053] The epoxy equivalent of the epoxy component (B) having a π-conjugated mesogenic skeleton is preferably 100 g / eq or more, particularly preferably 150 g / eq or more, and even more preferably 180 g / eq or more. The epoxy equivalent is preferably 500 g / eq or less, particularly preferably 400 g / eq or less, and even more preferably 300 g / eq or less. This improves the dispersibility of the thermally conductive filler (A) and facilitates the development of adhesive properties utilizing the epoxy groups. The epoxy equivalent in this specification is a value measured in accordance with JIS K7236.

[0054] The softening point of the epoxy component (B) having a π-conjugated mesogenic skeleton is preferably 40°C or higher, particularly preferably 50°C or higher, and even more preferably 60°C or higher. The softening point is preferably 200°C or lower, particularly preferably 150°C or lower, and even more preferably 120°C or lower. This improves the dispersibility of the thermally conductive filler (A). The softening point in this specification is a value measured in accordance with the ring and ball method described in JIS K7234:1986.

[0055] Examples of the epoxy component (B) that does not have a π-conjugated mesogen skeleton include glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenyl novolac, and cresol novolac; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidyl- or alkylglycidyl-type epoxy resins in which active hydrogen atoms bonded to nitrogen atoms, such as aniline isocyanurate, are substituted with glycidyl groups; so-called alicyclic epoxides in which epoxy groups are introduced by, for example, oxidizing carbon-carbon double bonds in the molecule, such as vinylcyclohexane diepoxide, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane; and multifunctional epoxy resins having three or more epoxy groups in the molecule. Preferred examples of polyfunctional epoxy resins include triphenylmethane epoxy resins, etc. These epoxy resins can be used alone or in combination of two or more.

[0056] When using an epoxy component (B) having a π-conjugated mesogenic skeleton, it is preferable to use the above-mentioned epoxy component (B) not having a π-conjugated mesogenic skeleton in combination, which allows for good adjustment of the tackiness and adhesiveness of the adhesive film.

[0057] Of the above, the epoxy component (B) not having a π-conjugated mesogenic skeleton is preferably a glycidyl ether of a phenol, and in particular, a bisphenol F epoxy resin is preferred. Furthermore, when an epoxy component (B) having a π-conjugated mesogenic skeleton is not used, the epoxy component (B) not having a π-conjugated mesogenic skeleton is preferably a combination of a glycidyl ether of a phenol and a multifunctional epoxy resin, among the above. As the glycidyl ether of a phenol, a bisphenol F epoxy resin is preferred, and as the multifunctional epoxy resin, a triphenylmethane epoxy resin is preferred. This allows the tackiness and adhesiveness of the adhesive film to be well adjusted.

[0058] The epoxy equivalent of the glycidyl ether of the above phenols is preferably 100 g / eq or more, particularly preferably 120 g / eq or more, and even more preferably 150 g / eq or more. The epoxy equivalent is preferably 500 g / eq or less, particularly preferably 400 g / eq or less, and even more preferably 300 g / eq or less. This results in superior tackiness and adhesiveness of the resulting adhesive film.

[0059] The epoxy equivalent of the polyfunctional epoxy resin is preferably 80 g / eq or more, particularly preferably 100 g / eq or more, and even more preferably 130 g / eq or more. The epoxy equivalent is preferably 400 g / eq or less, particularly preferably 300 g / eq or less, and even more preferably 200 g / eq or less. This ensures sufficient curability of the adhesive resin composition R, and facilitates the development of adhesive properties utilizing the epoxy groups.

[0060] The softening point of the polyfunctional epoxy resin is preferably 40°C or higher, particularly preferably 50°C or higher, and even more preferably 60°C or higher. The softening point is preferably 200°C or lower, particularly preferably 150°C or lower, and even more preferably 120°C or lower. This allows the resin to melt during curing (heat treatment), resulting in an adhesive composition R with sufficient curability and adhesiveness. Furthermore, the resin does not melt at or near room temperature, making it easy to handle.

[0061] The content (total content) of the epoxy component (B) in the adhesive film (adhesive resin composition R) is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, and even more preferably 20% by mass or more. When the lower limit of the content of the epoxy component (B) is as described above, the adhesive resin composition R is sufficiently cured, and it can exhibit better mechanical strength and adhesiveness. Furthermore, the content is preferably 45% by mass or less, more preferably 40% by mass or less, particularly preferably 35% by mass or less, and even more preferably 30% by mass or less. When the upper limit of the content of the epoxy component (B) is as described above, the contents of the other components can be ensured.

[0062] When an epoxy component (B) having a π-conjugated mesogenic skeleton and an epoxy component (B) not having a π-conjugated mesogenic skeleton are used in combination, the blending ratio (by mass) thereof is preferably 20:80 to 95:5, more preferably 40:60 to 90:10, particularly preferably 50:50 to 85:15, and even more preferably 60:40 to 80:20. This allows for a good balance between the dispersibility of the thermally conductive filler (A) and the tackiness and adhesiveness of the adhesive film.

[0063] Furthermore, when a glycidyl ether of a phenol is used in combination with a polyfunctional epoxy resin, the blending ratio (by mass) thereof is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, particularly preferably 15:85 to 85:15, and even more preferably 20:80 to 80:20, which allows for a good balance between the tackiness of the adhesive film before the curing reaction and the adhesiveness after the curing reaction.

[0064] (3) Hardener (C) When the epoxy component (B) requires a curing agent (C), the adhesive film according to this embodiment contains the curing agent (C) as an essential component. In this case, at least one of the epoxy component (B) and the curing agent (C) has a π-conjugated mesogenic skeleton.

[0065] Preferred examples of the curing agent (C) include phenols, amines, and thiols, and one type can be used alone or two or more types can be used in combination. Among these, phenols (phenol-based curing agents) are preferred from the viewpoint of reactivity with the epoxy component (B).

[0066] As the curing agent (C) having a π-conjugated mesogenic skeleton, phenols having a π-conjugated mesogenic skeleton are preferred, and as the phenols having a π-conjugated mesogenic skeleton, biphenyl-type phenols are particularly preferred.

[0067] Preferred examples of biphenyl-type phenolic resins include those represented by the following formula:

[0068] [ka]

[0069] [ka] (wherein n is an integer of 0 or more).

[0070] The hydroxyl equivalent of the biphenyl type phenolic resin is preferably 80 g / eq or more, particularly preferably 85 g / eq or more, and even more preferably 90 g / eq or more. The hydroxyl equivalent is preferably 300 g / eq or less, particularly preferably 280 g / eq or less, and even more preferably 250 g / eq or less. This prevents the inclusion of substances that inhibit the curing reaction, such as phenol alone, remaining as unreacted substances during synthesis, and This improves the curability of the epoxy component (B).

[0071] The softening point of the biphenyl phenolic resin is preferably 60°C or higher, particularly preferably 80°C or higher, and even more preferably 90°C or higher. The softening point is preferably 200°C or lower, particularly preferably 150°C or lower, and even more preferably 130°C or lower. When the biphenyl phenolic resin does not soften, its sublimation temperature is preferably 270°C or higher. The sublimation temperature is preferably 330°C or lower. A resin having a high softening point or high sublimation temperature effectively exhibits π-electron interactions, resulting in better dispersibility of the thermally conductive filler (A).

[0072] As the curing agent (C) having no π-conjugated mesogenic skeleton, phenols having no π-conjugated mesogenic skeleton are preferred, and as the phenols having no π-conjugated mesogenic skeleton, novolac-type phenolic resins are particularly preferred.

[0073] When using a curing agent (C) having a π-conjugated mesogenic skeleton, it is preferable to use the above-mentioned curing agent (C) not having a π-conjugated mesogenic skeleton in combination, which makes it possible to adjust the curability of the epoxy component (B).

[0074] The hydroxyl equivalent of the novolac phenolic resin is preferably 70 g / eq or more, particularly preferably 80 g / eq or more, and even more preferably 90 g / eq or more. The hydroxyl equivalent is preferably 300 g / eq or less, particularly preferably 280 g / eq or less, and even more preferably 250 g / eq or less. This results in superior curability of the epoxy resin. The hydroxyl equivalent in this specification is a value measured in accordance with JIS K0070.

[0075] The content (total content) of the curing agent (C) in the adhesive film (adhesive resin composition R) is preferably 2% by mass or more, more preferably 4% by mass or more, particularly preferably 5% by mass or more, and even more preferably 8% by mass or more. Furthermore, the content is preferably 40% by mass or less, more preferably 35% by mass or less, particularly preferably 30% by mass or less, and even more preferably 25% by mass or less. By ensuring that the content of the curing agent (C) is within the above range, the adhesive resin composition R can be cured more effectively.

[0076] When a biphenyl-type phenolic resin and a novolac-type phenolic resin are used in combination, the blending ratio (by mass) thereof is preferably 20:80 to 90:10, more preferably 30:70 to 80:20, particularly preferably 35:65 to 75:25, and even more preferably 40:60 to 70:30, which allows for a good balance between the curability of the adhesive resin composition R and the dispersibility of the thermally conductive filler (A).

[0077] (4) Binder polymer (D) The binder polymer (D) is blended for the purposes of forming the adhesive resin composition R into a film, imparting appropriate tack to the resulting adhesive film, etc. Examples of such binder polymers that can be used include acrylic polymers, polyester resins, phenoxy resins, urethane resins, silicone resins, and rubber-based polymers, with acrylic polymers being particularly preferred.

[0078] Examples of acrylic acid polymers include (meth)acrylic acid ester polymers obtained by polymerizing (meth)acrylic acid ester monomers. In this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0079] Examples of monomers constituting the (meth)acrylic acid ester polymer include (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate, as well as functional group-containing monomers having a functional group in the molecule. Preferred examples of functional group-containing monomers include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), and monomers having an amino group in the molecule (amino group-containing monomers). These may be used alone or in combination of two or more.

[0080] The (meth)acrylic acid ester polymer used as the binder polymer (D) in this embodiment is preferably a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 18 carbon atoms and a functional group-containing monomer. The number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester is preferably 1 to 9, particularly preferably 1 to 6, and further preferably 1 to 3. As the (meth)acrylic acid alkyl ester, methyl (meth)acrylate is particularly preferred, and methyl acrylate is most preferred.

[0081] The functional group-containing monomer is preferably a hydroxyl group-containing monomer. Examples of the hydroxyl group-containing monomer include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate is particularly preferred, and 2-hydroxyethyl acrylate is most preferred.

[0082] By using the above-mentioned monomer, it becomes easier to disperse the thermally conductive filler (A) in the adhesive resin composition R well.

[0083] When a (meth)acrylic acid ester polymer obtained by copolymerizing the above-mentioned (meth)acrylic acid alkyl ester with a functional group-containing monomer is used as the binder polymer (D), the (meth)acrylic acid ester polymer preferably contains structural units derived from the functional group-containing monomer in an amount of 5 to 90 mass %, more preferably in an amount of 8 to 80 mass %, and even more preferably in an amount of 10 to 60 mass %.

[0084] The weight-average molecular weight of the acrylic polymer ((meth)acrylic acid ester polymer) used as the binder polymer (D) is preferably 50,000 or more, more preferably 100,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. The weight-average molecular weight is preferably 1,000,000 or less, more preferably 700,000 or less, particularly preferably 500,000 or less, and even more preferably 400,000 or less. Having a weight-average molecular weight within the above range improves film-forming properties and adhesiveness, and also improves the dispersibility of the thermally conductive filler (A). The weight-average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0085] The glass transition temperature (Tg) of the acrylic polymer ((meth)acrylic acid ester polymer) used as the binder polymer (D) is preferably −20°C or higher, more preferably −15°C or higher, particularly preferably −10°C or higher, and even more preferably −5°C or higher. The glass transition temperature (Tg) is preferably 60°C or lower, more preferably 50°C or lower, particularly preferably 40°C or lower, and even more preferably 35°C or lower. Having a glass transition temperature (Tg) within the above range improves film-forming properties and adhesiveness, and also improves the dispersibility of the thermally conductive filler (A). The glass transition temperature (Tg) of the (meth)acrylic acid ester polymer used herein is a value calculated based on the FOX formula.

[0086] The content of the binder polymer (D) in the adhesive film (adhesive resin composition R) is preferably 1% by mass or more, more preferably 2% by mass or more, particularly preferably 3% by mass or more, and even more preferably 4% by mass or more. Furthermore, the content is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 25% by mass or less. By ensuring that the content of the binder polymer (D) is within the above range, the mechanical strength and adhesiveness of the cured product of the adhesive film are maintained at a good level, while the film-forming properties and adhesiveness are improved, and the dispersibility of the thermally conductive filler (A) is improved.

[0087] (5) Curing accelerator (E) The adhesive film according to this embodiment preferably further contains a curing accelerator (E) that accelerates or adjusts the reaction between the epoxy component (B) and the curing agent (C) described above.

[0088] Examples of the curing accelerator (E) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organic phosphines such as tributylphosphine, diphenylphosphine, and triphenylphosphine; and tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. These may be used alone or in combination of two or more.

[0089] When a phenol is used as the curing agent (C), it is preferable to use an imidazole-based curing accelerator from the viewpoints of curing reaction reactivity, storage stability, physical properties of the cured product, curing speed, etc., and 2-phenyl-4,5-hydroxymethylimidazole is particularly preferably used.

[0090] The content of the curing accelerator (E) in the adhesive film (adhesive resin composition R) is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, particularly preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more. Furthermore, the content is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less. By ensuring that the content of the curing accelerator (E) is within the above range, the storage stability of the adhesive film is improved, and the adhesive resin composition R can be cured well.

[0091] (6) Various additives If desired, various additives such as a tackifier, a flame retardant, an antioxidant, a light stabilizer, a softener, and a rust inhibitor may be added to the adhesive resin composition of the present embodiment.

[0092] 2. Preparation of adhesive resin composition The adhesive resin composition R in this embodiment can be obtained by thoroughly mixing a thermally conductive filler (A) consisting of at least one of two-dimensional graphene and single-layer boron nitride, an epoxy component (B), a binder polymer (D), and optionally a curing agent (C), a curing accelerator (E), additives, and a solvent. When any of the above components is used in a solid state, or when precipitation occurs when mixed with other components in an undiluted state, the component may be dissolved or diluted in a solvent before being mixed with the other components.

[0093] In the adhesive resin composition R of this embodiment, it is preferable to first mix the thermally conductive filler (A) and the binder polymer (D) in a solvent, and then add the epoxy component (B) and, if desired, the curing agent (C), the curing accelerator (E), additives, etc. By mixing the thermally conductive filler (A) and the binder polymer (D) in advance before blending the epoxy component (B), etc., the dispersibility of the thermally conductive filler (A) is improved, and segregation of the thermally conductive filler (A) in the coating film is suppressed. As a result, the thermally conductive filler (A) is uniformly dispersed in the resulting adhesive film, and an adhesive film with superior thermal conductivity can be obtained.

[0094] The thermally conductive filler (A) and the binder polymer (D) are mixed in a solvent by stirring at a disperser rotation speed of 500 to 5,000 rpm for 10 minutes or more, and more preferably at a disperser rotation speed of 1,000 to 40,000 rpm for 20 minutes or more.

[0095] The solvent is not particularly limited, and examples thereof include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolve-based solvents such as ethyl cellosolve; N,N-dimethylformamide, trimethyl-2-pyrrolidone, and butyl carbitol. Methyl ethyl ketone is preferred.

[0096] The viscosity of the coating solution of the adhesive resin composition R prepared in this manner is not particularly limited as long as it is within a range that allows coating, and can be appropriately selected depending on the situation. Note that the addition of a dilution solvent or the like is not a necessary condition, and as long as the adhesive resin composition R has a viscosity that allows coating, it is not necessary to add a dilution solvent.

[0097] 3. Manufacturing of adhesive film The adhesive film according to this embodiment can be obtained by forming the adhesive resin composition R obtained above into a film. When forming the adhesive resin composition R into a film, it is preferable to use a release sheet as the coating target. For example, the adhesive film according to this embodiment can be easily produced by applying a coating liquid of the adhesive resin composition R to a release sheet and removing the dilution solvent by heating and drying.

[0098] Examples of the release sheet include resin films, nonwoven fabrics, and paper, with resin films being commonly used. Examples of resin films include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene vinyl acetate films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester copolymer films, polystyrene films, polycarbonate films, polyimide films, and fluororesin films. Crosslinked films of these may also be used. Furthermore, laminated films of these may also be used.

[0099] The release surface of the release sheet (the surface that comes into contact with the adhesive resin composition R) is preferably subjected to a release treatment. Examples of release agents used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. However, this release treatment is not always necessary.

[0100] There are no particular restrictions on the thickness of the release sheet, but it is usually about 20 to 150 μm.

[0101] In one example of producing an adhesive film, a coating liquid of the adhesive resin composition R is applied to the release surface of a release sheet. Examples of coating methods that can be used include bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0102] Next, the coating film of the adhesive resin composition R is dried to volatilize the dilution solvent and the like, thereby obtaining an adhesive film. Drying conditions are preferably 90 to 150°C for 0.5 to 30 minutes, and particularly preferably 100 to 120°C for 1 to 10 minutes. The heating temperature for the drying treatment must be lower than the thermosetting temperature of the adhesive resin composition R.

[0103] After the drying treatment, it is preferable to laminate another peelable protective film on the exposed surface of the adhesive film to protect the adhesive film. At this time, the protective film is laminated so that the release surface of the peelable protective film contacts the exposed surface of the adhesive film. This results in a laminate consisting of a release sheet / adhesive film / protective film.

[0104] The protective film may be the same as the release sheet mainly made of a resin film as described above. The protective film may or may not be release-treated, as long as it has releasability from the adhesive film.

[0105] The adhesive film (laminate) obtained as described above is preferably heat-pressed. By heat-pressing the adhesive film, voids present inside the adhesive film can be reduced, resulting in better thermal conductivity. Specifically, heat-pressing makes it easier for the thermally conductive fillers (A) to come into contact with each other, making it easier to form thermal conduction paths, resulting in better thermal conductivity. By performing such heat-pressing, the amount of thermally conductive filler (A) blended in the adhesive film can be further reduced, and the flexibility and adhesiveness of the adhesive film can be further improved.

[0106] The heating temperature of the heat press is set to be lower than the curing reaction temperature of the epoxy component (B), specifically, preferably 30 to 90°C, more preferably 40 to 80°C, particularly preferably 45 to 70°C, and even more preferably 45 to 60°C.

[0107] The pressure of the heat press is preferably 0.5 to 15 MPa, more preferably 1 to 10 MPa, particularly preferably 1.5 to 5 MPa, and further preferably 2 to 4 MPa.

[0108] The time for the heat pressing is preferably 0.5 to 60 minutes, more preferably 1 to 40 minutes, particularly preferably 2 to 30 minutes, and further preferably 3 to 20 minutes.

[0109] 4. Physical properties of adhesive film (1) Thickness of adhesive film The thickness (measured in accordance with JIS K7130) of the adhesive film according to this embodiment (including both non-heat-pressed and heat-pressed adhesive films) is preferably 0.5 μm or more as a lower limit, more preferably 1 μm or more, particularly preferably 5 μm or more, and even more preferably 10 μm or more. When the lower limit of the adhesive film thickness is as above, it is likely to exhibit good adhesive strength and adhesion.

[0110] Furthermore, the upper limit of the thickness of the adhesive film according to this embodiment is preferably 1000 μm or less, more preferably 500 μm or less, particularly preferably 200 μm or less, and even more preferably 100 μm or less. When the upper limit of the adhesive film thickness is as described above, the thermal conductivity becomes better. The adhesive film may be formed as a single layer, or may be formed by laminating multiple layers.

[0111] (2) Raman peak intensity ratio D / G For the adhesive film according to this embodiment (including adhesive films that are not heat-pressed and adhesive films that are heat-pressed), the wavenumber in the absorption spectrum obtained by Raman measurement was 1570 cm -1 The peak value of the G band absorption intensity (I G ) for the wavenumber 1250 cm -1 The peak value of the D band absorption intensity (I D ) (hereinafter sometimes referred to as "Raman peak intensity ratio D / G") is preferably 0.5 or less, more preferably 0.4 or less, particularly preferably 0.3 or less, and even more preferably 0.2 or less. When the Raman peak intensity ratio D / G is within the above range, it is understood that the thermally conductive filler (A) contains a good crystalline structure. As a result, the adhesive film exhibits excellent thermal conductivity due to the thermally conductive filler (A). There is no particular restriction on the lower limit of the Raman peak intensity ratio D / G, but it is usually preferably 0.001 or more. The specific measurement method for Raman measurement in this specification is as shown in the test examples described later. In addition, the wave number 1570 cm -1 The G-band peak near the wavenumber 1570 cm -1 ±100cm from the center -1 The peak intensity (I G ) indicates the relative value of the absorption intensity at the peak top obtained by measurement. -1 The D band peak near the wavenumber of 1250 cm -1 ±100cm from the center -1 The peak intensity (I D ) indicates the relative value of the absorption intensity at the peak top obtained by measurement.

[0112] (3) Adhesive strength The adhesive strength of the adhesive film according to this embodiment (including both non-heat-pressed and heat-pressed adhesive films) to a silicon wafer (arithmetic mean roughness (Ra): 0.02 μm or less) is preferably 0.1 mN / 25 mm or more, more preferably 0.5 mN / 25 mm or more, particularly preferably 0.8 mN / 25 mm or more, and even more preferably 1.0 mN / 25 mm or more. This allows for good adhesion to the adherend and excellent temporary adhesion.

[0113] The upper limit of the adhesive strength is not particularly limited, but is generally preferably 5.0 mN / 25 mm or less, more preferably 3.0 mN / 25 mm or less, and particularly preferably 2.0 mN / 25 mm or less. This results in excellent reworkability. Note that the adhesive strength in this specification basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2009, and the specific measurement method is as shown in the test examples described below.

[0114] (4) Thermal conductivity after heat curing The thermal conductivity of the adhesive film according to this embodiment after thermal curing (cured product) is preferably 4 W / mK or more, and particularly preferably 5 W / mK or more. This means that the cured product of the adhesive film has excellent thermal conductivity. The adhesive film according to this embodiment can achieve such high thermal conductivity by having the above-mentioned configuration. The method for measuring thermal conductivity in this specification is as shown in the test examples described below.

[0115] (5) Shear adhesive strength after heat curing The shear adhesive strength of the adhesive film according to this embodiment after heat curing (cured body) is 90N / 5×5mm 2 More preferably, it is 100N / 5×5mm or more. 2It is preferable that the above is satisfied. As a result, it can be said that the cured product of the adhesive film has excellent mechanical strength. The adhesive film according to this embodiment can achieve such high shear adhesive strength by having the above-mentioned configuration. The method for measuring the shear adhesive strength in this specification is as shown in the test examples described below.

[0116] [Adhesive film with support sheet] An adhesive film with a support sheet according to one embodiment of the present invention comprises the above-mentioned adhesive film (including adhesive films that are not heat-pressed and adhesive films that are heat-pressed) and a support sheet laminated on at least one side of the adhesive film. The support sheet may be peeled off from the adhesive film in the future.

[0117] By supporting the adhesive film on the support sheet, for example, the workability of the adherend can be improved. For example, even if it is difficult to process the adherend using the adhesive film alone, it is possible to perform a process in which the adhesive film with the support sheet is attached to a first adherend, processing is performed in that state, and then the support sheet is peeled off and the adhesive film is attached to a second adherend.

[0118] An example of an adhesive film with a support sheet according to this embodiment is shown in Figure 1. The adhesive film with a support sheet 2 shown in Figure 1 is composed of an adhesive film 1, a support sheet 11 laminated on one side of the adhesive film 1 (the upper side in Figure 1), and a release sheet 12 laminated on the other side of the adhesive film 1 (the lower side in Figure 1). The release sheet 12 is laminated on the adhesive film 1 so that its releasable side contacts the adhesive film 1. The release sheet 12 protects the adhesive film 1 until it is used, and may be omitted. Furthermore, in the adhesive film with a support sheet according to this embodiment, a protective film may be laminated instead of the release sheet 12.

[0119] The support sheet 11 is not particularly limited as long as it can exhibit sufficient mechanical strength to support the adhesive film 1. Examples of materials constituting the support sheet 1 include resin films, nonwoven fabrics, and paper, but resin films are generally used.

[0120] Specific examples of resin films include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film; polyolefin films such as polypropylene film, ethylene-propylene copolymer film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film; ethylene copolymer films such as ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, and ethylene-(meth)acrylic acid ester copolymer film; polyvinyl chloride films such as polyvinyl chloride film and vinyl chloride copolymer film; polyester films such as polyethylene terephthalate film and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; and fluororesin films. Modified films such as crosslinked films and ionomer films may also be used. Furthermore, laminate films may be formed by laminating multiple of the above films, either the same or different types. The support sheet 11 may also be a release sheet. The support sheet 11 may also be, for example, a sheet having a known adhesive layer provided on the above-mentioned resin film, nonwoven fabric, paper, or the like.

[0121] The thickness of support sheet 11 is preferably 20 μm or more, particularly preferably 40 μm or more, and even more preferably 60 μm or more. Furthermore, the thickness is preferably 150 μm or less, particularly preferably 120 μm or less, and even more preferably 110 μm or less. Having a thickness within the above range makes support sheet 11 more likely to have the desired mechanical strength, and the adherend processability and the like are improved.

[0122] The adhesive film 2 with support sheet may be a dicing / die-bonding sheet used in manufacturing a semiconductor device. In this case, the adhesive film 2 with support sheet can be used in the process of dicing and die-bonding a semiconductor element, and the cured adhesive film functions as a thermal conductor for dissipating heat generated when the semiconductor device is operating. In this case, the support sheet 11 is preferably, for example, the above-mentioned resin film having a known pressure-sensitive adhesive layer provided on the surface facing the adhesive film 1.

[0123] As an example of a method for manufacturing an adhesive film 2 with a support sheet, the release sheet may be peeled off from the laminate consisting of the release sheet / adhesive film / protective film described above and a support sheet may be laminated on it, or the protective film may be peeled off from the laminate consisting of the release sheet / adhesive film / protective film described above and a support sheet may be laminated on it, or a support sheet may be used instead of the protective film in the method for manufacturing an adhesive film described above.

[0124] [Structure] A structure according to one embodiment of the present invention is formed by bonding at least a part of a first member and at least a part of a second member via the cured product of the adhesive film described above.

[0125] An example of a structure according to this embodiment is shown in Fig. 2. The structure 3 shown in Fig. 2 includes a first member 31, a second member 32, and a hardened body 1A provided between the first member 31 and the second member 32.

[0126] The cured body 1A is obtained by completely curing the above-mentioned adhesive film (adhesive film 1; including both non-heat-pressed and heat-pressed adhesive films) through a heat treatment. The first member 31 and the second member 32 are fixed to each other by the adhesiveness of the cured body 1A (adhesive film). The shapes of the first member 31 and the second member 32 in this embodiment are not particularly limited, and may be a flexible sheet, a plate, a block, or the like.

[0127] The first member 31 (or the second member 32) in this embodiment is not particularly limited, but is preferably, for example, a member that generates heat while performing a predetermined function and that is required to suppress temperature rise, or a member that is required to control the flow of heat generated by the member in a specific direction (heat-generating member). The second member 32 (or the first member 31) is also not particularly limited, but is preferably, for example, a member that dissipates heat that it receives, or a member that transfers heat that it receives to another member (heat-transfer member). The cured body 1A in this embodiment has excellent thermal conductivity, and therefore functions as a thermal conductor that transfers heat from the first member 31 that generates heat to the second member 32 and releases the heat to the outside.

[0128] Examples of heat-generating members include semiconductor devices such as thermoelectric conversion devices, photoelectric conversion devices, and large-scale integrated circuits, electronic devices such as LED light-emitting elements, optical pickups, and power transistors, various electronic devices such as mobile terminals and wearable terminals, batteries, electric cells, motors, and engines. Furthermore, heat-transfer members are preferably made of highly conductive materials, such as metals such as aluminum, stainless steel, and copper, graphite, and carbon nanofibers. The form of the heat-transfer member is not particularly limited and may be a substrate, a housing, a heat sink, a heat spreader, or the like.

[0129] As an example, the first member 31 is preferably a semiconductor element, and as an example, the second member 32 is preferably a substrate. In this case, when the semiconductor element, which is the first member 31, generates heat, the heat from the semiconductor element is dissipated through the cured body 1A and then through the substrate, which is the second member 32. A semiconductor device composed of the above members can be manufactured by using the above-mentioned adhesive film 2 with support sheet as a dicing / die bonding sheet.

[0130] Also, as an example, the second member 32 may be a semiconductor element instead of a substrate. In this case, when the semiconductor element serving as the first member 31 or the second member 32 generates heat, the heat from the heated semiconductor element is conducted to the other semiconductor element via the cured body 1A, and the temperatures of the respective semiconductor elements are made uniform. This prevents damage to the structure 3 (semiconductor device) due to thermal stress or the like.

[0131] To manufacture the structure 3 according to this embodiment, one side of the adhesive film described above is attached to the first member 31 (or the second member 32), and then the other side of the adhesive film is attached to the second member 32 (or the first member 31). When using the adhesive film 2 with the support sheet described above, the release sheet 12 is peeled off, and one side of the exposed adhesive film 1 is attached to the first member 31 (or the second member 32), and then the support sheet 11 is peeled off, and the other side of the exposed adhesive film 1 is attached to the second member 32 (or the first member 31).

[0132] The adhesive film used to manufacture the structure 3 according to this embodiment may be either a non-heat-pressed adhesive film or a heat-pressed adhesive film, but it is preferable to use a heat-pressed adhesive film. Alternatively, a non-heat-pressed adhesive film may be used, and the adhesive film may be heat-pressed after being attached to the first member 31 (or the second member 32) or after the first member 31 and the second member 32 are attached via the adhesive film. However, if a pre-heat-pressed adhesive film is used, damage to the first member 31 and / or the second member 32 due to the heat press can be prevented.

[0133] When laminating the first member 31 and the second member 32 via the adhesive film, or when attaching the adhesive film to the first member 31 or the second member 32, it is preferable to carry out the lamination or attachment at a temperature (hereinafter sometimes referred to as the "attachment temperature") equal to or higher than the temperature (hereinafter sometimes referred to as the "tan δ peak temperature") at which the loss tangent (tan δ) obtained by measuring the viscoelasticity of the adhesive film before any heat treatment reaches its peak. By carrying out the lamination or attachment at such a temperature, the adhesive film becomes flexible, which makes it possible to more effectively prevent air from being trapped between the adhesive film and the adherend, thereby improving the thermal conductivity between the adhesive film and the adherend.

[0134] When the first member 31 is a flexible sheet-like member, and a laminate of the sheet-like member and adhesive film is attached to the second member 32, or when the adhesive film with support sheet 2 is attached to the first member 31 or the second member 32, the above-mentioned effect of suppressing entrapment of air becomes even better. Because the laminate of the sheet-like member and adhesive film and the adhesive film with support sheet 2 are flexible and easily pliable, they can be gradually brought into close contact with the adherend from one direction to another, and can be attached while pushing out air.

[0135] The application temperature is preferably 0 to 50° C. higher than the tan δ peak temperature, more preferably 3 to 30° C. higher, and even more preferably 5 to 20° C. The upper limit of the application temperature must be lower than the curing temperature of the adhesive film, and specifically is preferably 120° C. or lower, more preferably 100° C. or lower, and even more preferably 90° C. or lower.

[0136] As described above, one side of the adhesive film is attached to the first member 31 (or the second member 32) and the other side of the adhesive film is attached to the second member 32 (or the first member 31), and then a heat treatment is performed to completely harden the adhesive film into a hardened body 1A, thereby obtaining the structure 3 of this embodiment.

[0137] The heat treatment preferably includes a preheating step in which the adhesive film is maintained at a temperature (hereinafter sometimes referred to as the "preheating temperature") below which the adhesive film loses 0.5% weight when thermogravimetrically measured under conditions of heating from 40°C to 400°C at a rate of 10°C / min in an air atmosphere before any heat treatment, for 30 minutes or more, and a complete curing step in which the adhesive film is completely cured after the preheating step. If the adhesive film is completely cured by a rapid heat treatment, low-molecular-weight components in the adhesive film tend to volatilize and foam due to the heat, resulting in the formation of voids within the adhesive film. In contrast, if the heat treatment includes the above steps, the low-molecular-weight components are trapped in the matrix of the epoxy component (B) or binder polymer (D) before volatilizing, thereby suppressing foaming and reducing the voids in the adhesive film. This results in improved thermal conductivity of the resulting cured product. By subjecting the adhesive film according to this embodiment to the above-described heat pressing and the above-described preheating step, the voids in the resulting cured product can be more effectively reduced.

[0138] The preheating temperature is preferably 1 to 50° C. lower than the temperature at which the adhesive film loses 0.5% weight, particularly preferably 10 to 40° C. lower, and even more preferably 15 to 30° C. lower. The lower limit of the preheating temperature is preferably 80° C. or higher, particularly preferably 90° C. or higher, and even more preferably 100° C. or higher.

[0139] The preheating step is preferably carried out for 30 minutes or more, more preferably for 30 to 120 minutes, and even more preferably for 30 to 60 minutes.

[0140] The heat treatment preferably includes the above preheating step followed by a complete curing step at a heating temperature sufficient to completely cure the adhesive film. The heating temperature in the complete curing step must be higher than the above preheating temperature, and is preferably 5 to 100°C higher than the preheating temperature, particularly preferably 10 to 70°C higher, and even more preferably 20 to 50°C higher. Specifically, the heating temperature in the complete curing step is preferably 85 to 200°C, particularly preferably 100 to 190°C, and even more preferably 120 to 180°C.

[0141] The complete curing step is preferably carried out for 30 to 180 minutes, more preferably for 45 to 150 minutes, and even more preferably for 60 to 120 minutes.

[0142] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0143] For example, the release sheet 12 laminated on the adhesive film 1 in Fig. 1 may be omitted. Furthermore, the shape of the first member and the first member in the structure is not limited to that shown in Fig. 2, and may have various shapes. [Example]

[0144] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0145] [Examples 1 to 4, Comparative Examples 1 to 5] The thermally conductive filler (A) (components (a-1) to (a-3)) and binder polymer (D) (component (d)) shown below were mixed and diluted with methyl ethyl ketone to a solids concentration of 15% by mass. The mixture was stirred in a disperser at 3,000 rpm for at least 30 minutes to dissolve and disperse the mixture. Meanwhile, the epoxy component (B) (components (b-1) to (b-5)), curing agent (C) (components (c-1) to (c-3)), and curing accelerator (E) (component (e)) shown below were each dispersed in methyl ethyl ketone to a solids concentration of 10 to 70% by mass. These dispersions were then blended with the above dispersion, and methyl ethyl ketone was added to bring the total solids concentration to 25% by mass. The resulting mixture was stirred for 10 minutes in a planetary centrifugal mixer (Thinky Corporation, product name "AR-100") to obtain a coating solution for the adhesive resin composition. The type and content (in terms of solid content) of each component in the adhesive resin composition are as shown in Table 1. The coating liquid of this adhesive resin composition was also used to prepare a sample for measuring adhesive strength in Test Example 2 (adhesive strength measurement) described later.

[0146] Thermally conductive filler (A) (a-1) Thermally conductive filler (having a two-dimensional crystal structure): graphene (manufactured by ADEKA Corporation, product name "CNS-1A1", average particle size 12 μm, thickness 50 nm or less, Raman peak intensity ratio D / G = 0.1, when measured by X-ray diffraction using a CuKα radiation source (wavelength 0.15418 nm), peaks were detected at 2θ positions of 26.6° and 42.4°) (a-2) Thermally conductive filler: reduced graphene oxide (manufactured by ANGSTRON MATERIALS, product name "N002-PDR", average particle size 8-10 μm, thickness 1.0-1.2 nm, Raman peak intensity ratio D / G = 1.3, when measured by X-ray diffraction using a CuKα radiation source (wavelength 0.15418 nm), no peak was detected at 2θ of 26.6°) (a-3) Thermally conductive filler: graphite (manufactured by Nippon Graphite Co., Ltd., product name "CSP-E", average particle size 8 μm, thickness 8 μm, Raman peak intensity ratio D / G = 0.1, when measured by X-ray diffraction using a CuKα radiation source (wavelength 0.15418 nm), peaks were detected at 2θ positions of 26.6° and 42.4°)

[0147] Epoxy component (B) (b-1) Epoxy component: an epoxy resin having a naphthalene skeleton represented by the following formula (1) (solid, manufactured by Nippon Kayaku Co., Ltd., product name "NC-7000L", epoxy equivalent 223 to 238 g / eq, ICI viscosity (150°C) 0.50 to 1.00 Pa·s, softening point 83 to 93°C) [ka] (wherein n is an integer of 0 or more).

[0148] (b-2) Epoxy component: an epoxy resin having a biphenyl skeleton represented by the following formula (2) (solid, manufactured by Nippon Kayaku Co., Ltd., product name "NC-3000H", epoxy equivalent 280 to 300 g / eq, ICI viscosity (150°C) 0.25 to 0.35 Pa s, softening point 65 to 75°C) [ka] (wherein n is an integer of 0 or more).

[0149] (b-3) Epoxy component: bisphenol F type epoxy resin (liquid, manufactured by Mitsubishi Chemical Corporation, product name "YL983U", epoxy equivalent 165 to 175 g / eq, viscosity (25°C) 3.0 to 6.0 Pa·s) (b-4) Epoxy component: Multifunctional epoxy resin (solid, manufactured by Nippon Kayaku Co., Ltd., product name "EPPN-502H", epoxy equivalent 158~178g / eq, ICI viscosity (150℃) 0.01~0.35Pa s, softening point 60~72℃) (b-5) Epoxy component: Cresol novolac epoxy resin (solid, manufactured by Nippon Kayaku Co., Ltd., product name "EOCN-104S", epoxy equivalent 213-223 g / eq, ICI viscosity (150°C) 2.55-3.45 Pa·s, softening point 90-94°C)

[0150] Hardener (C) (c-1) Curing agent: a biphenyl-type phenol compound represented by the following formula (3) (manufactured by Honshu Chemical Industry Co., Ltd., product name "BP", hydroxyl group equivalent 93.1 g / eq, sublimation temperature 283°C) [ka]

[0151] (c-2) Hardener: Novolac phenolic resin (manufactured by Asahi Organic Materials Co., Ltd., product name "PAPS-PN4", hydroxyl equivalent 104 g / eq, ICI viscosity (150°C) 3.0 Pa·s, softening point 111°C) (c-3) Hardener: Multifunctional phenolic resin (manufactured by Meiwa Kasei Co., Ltd., product name "MHE-7500", hydroxyl equivalent 95-99 g / eq, ICI viscosity (150°C) 0.73-1.03 Pa·s, softening point 107-113°C)

[0152] Binder polymer (D) (d) Binder polymer: Acrylic acid ester polymer (manufactured by Mitsubishi Chemical Corporation, product name "Coponyl N-4617", a copolymer obtained by copolymerizing 85 parts by mass of methyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate, weight average molecular weight: 300,000, glass transition temperature: 6°C) dissolved in a 1:1 mixed solvent of ethyl acetate and toluene (solid concentration 36% by mass)

[0153] Curing accelerator (E) (e) Curing accelerator: 2-phenyl-4,5-hydroxymethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., product name "Curezol 2PHZ")

[0154] The adhesive resin composition coating solution obtained in the above process was applied with an applicator to the release-treated surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET3811(S)"), one side of which had been release-treated with a silicone-based release agent, and then heated and dried at 100°C for 2 minutes to form an adhesive film (thickness: 50μm). The adhesive film with the release sheet was then bonded to the release-treated surface of a protective film (manufactured by Lintec Corporation, product name "SP-PET3811(S)"), one side of which had been release-treated with a silicone-based release agent, to obtain a laminate consisting of the release sheet, adhesive film (thickness: 50μm), and protective film.

[0155] The laminate obtained above was subjected to a pressure of 3.0 MPa at 50°C for 10 minutes using a hydraulic hot press to heat-press the adhesive film. This heat-pressing almost completely eliminated any voids present inside the adhesive film. In this way, a heat-pressed laminate consisting of a release sheet, a heat-pressed adhesive film (thickness: 22 μm), and a protective film was obtained.

[0156] [Test Example 1] <Raman Measurement> The laminates obtained in the examples and comparative examples after heat pressing were subjected to Raman measurement using a microscopic laser Raman spectrometer (manufactured by Thermo Fisher Scientific, product name "DXR2"). The absorption spectrum measured at a laser wavelength of 532 nm was obtained from a graph of the absorption spectrum at a wave number of 1570 cm. -1 The peak value of the G band absorption intensity (I G ) and a wave number of 1250 cm -1 The peak value of the D band absorption intensity (I D ) and the absorption intensity peak value (I G ) for the absorption intensity peak value (I D ) (Raman peak intensity ratio D / G) was calculated.

[0157] The results of Raman measurements on the adhesive film of Example 1 and the adhesive film of Comparative Example 2 are shown in Figures 3 and 4, respectively. In the graph of Figure 3, the wavelength at 1250 cm -1 The peak value of the D band absorption intensity (I D ) is small, while the wave number is 1570 cm -1 The peak value of the G band absorption intensity (I G ) is large. G ) for the absorption intensity peak value (I D ) (Raman peak intensity ratio D / G) is calculated to be 0.1.

[0158] In the graph of Figure 4, the wave number is 1250 cm -1 The peak value of the D band absorption intensity (I D ) and a wave number of 1570 cm -1 The peak value of the G band absorption intensity (I G ) are almost the same magnitude. G ) for the absorption intensity peak value (I D ) (Raman peak intensity ratio D / G) was calculated to be 1.3. The results, including those of other examples and comparative examples, are shown in Table 2.

[0159] [Test Example 2] <Adhesive strength measurement> The coating liquid of the adhesive resin composition obtained in the examples and comparative examples was coated on one side of a polyethylene terephthalate film with a thickness of 12 μm, and then dried by heating at 100°C for 2 minutes to produce a laminate in which an adhesive film (thickness: 50 μm) was firmly bonded to the polyethylene terephthalate film.

[0160] Next, for the purpose of surface protection of the adhesive film, the release-treated surface of a release film (manufactured by Lintec Corporation, product name "SP-PET381031", thickness 38 μm) was attached to the adhesive film side of the laminate. The resulting laminate was heat-pressed using a hydraulic heat press at 50°C for 10 minutes at a pressure of 3.0 MPa. The laminate was then cut together with the release film to obtain a 25 mm wide sample for measuring adhesive strength.

[0161] As an adherend, a silicon wafer (manufactured by Science and Technology Research Institute, diameter: 150 mm, thickness: 500 μm) was prepared, the surface of which had been subjected to chemical mechanical polishing to an arithmetic mean roughness (Ra) of 0.02 μm or less. The release film was peeled off from the adhesive strength measurement sample, and the exposed surface of the adhesive film was attached to the treated surface of the silicon wafer in an atmosphere of 80°C, obtaining a laminate consisting of the silicon wafer and the adhesive strength measurement sample.

[0162] The resulting laminate was left for 20 minutes in an atmosphere of 23°C and 50% relative humidity, and then subjected to a 180° peel test at a peel rate of 300 mm / min using a universal tensile tester (Instron, product name "Model 5581 Tester") in accordance with JIS Z0237:2000. The load during this 180° peel test was measured, and this measurement value was taken as the adhesive strength (N / 25 mm). The results are shown in Table 2.

[0163] [Test Example 3] <Evaluation of brittleness> The heat-pressed laminates obtained in the Examples and Comparative Examples were cut into 1 cm widths, and the two release films were peeled off. The resulting heat-pressed adhesive film was stretched at a tensile speed of 50 mm / min using a universal tensile tester (Instron, product name "Model 5581 Tester"). The phenomenon observed at this time was evaluated as the brittleness of the adhesive film according to the following criteria. The results are shown in Table 2. ○: Elongated by 1.1 times or more. △: Elongation occurred, but not by 1.1 times or more. ×: No elongation and waste was generated during cutting.

[0164] [Test Example 4] <Measurement of thermal conductivity> The heat-pressed laminates obtained in the examples and comparative examples were heat-treated at 125°C for 1 hour (preheating step), and then heat-treated at 175°C for 2 hours (complete curing step), to completely cure the heat-pressed adhesive film and form a cured product.

[0165] The resulting cured adhesive film was cut into square samples with sides of 5 mm. The thermal diffusivity of the cured adhesive film was measured using a thermal conductivity measuring device (manufactured by Aiphase, product name Aiphase Mobile 1U). The thermal diffusivity was then multiplied by the specific gravity and specific heat to calculate the thermal conductivity (W / mK) of the cured adhesive film. The results are shown in Table 2.

[0166] [Test Example 5] <Measurement of shear adhesive strength> (1) Preparation of the substrate chip One side of a silicon wafer (150 mm diameter, 350 μm thick) was polished with a #2000 grinding machine (DISCO, product name "DFG8540"). Dicing tape (Lintec, product name "Adwill D-175") was attached to the side of the silicon wafer opposite the polished side using a tape mounter (Lintec, product name "Adwill RAD2500"), and the silicon wafer was fixed to a wafer dicing ring frame with the polished side facing up. Next, using a dicing machine (DISCO, product name "DFD6362"), the dicing tape substrate was diced with a 20 μm cut to produce 5 mm x 5 mm adherend chips (adherend 1).

[0167] In addition, one side of a silicon wafer (200 mm diameter, 350 μm thick) was dry polished using a wafer backside grinding machine (DISCO, product name "DGP8760") to reduce the surface roughness (Ra) to 0.12 μm or less. Dicing tape (Lintec, product name "Adwill D-175") was attached to the side of the silicon wafer opposite the dry polished surface in the same manner as above, and the silicon wafer was fixed to a wafer dicing ring frame with the dry polished surface facing up. Next, the silicon wafer was diced in the same manner as above to produce 12 mm x 12 mm adherend chips (adherend 2).

[0168] (2) Preparation of test specimens The first release sheet was peeled off from the heat-pressed laminate obtained in the Examples and Comparative Examples, and the exposed surface of the heat-pressed adhesive film was attached to the polished surface of the adherend 1 obtained in the above step (1) at 80° C. Then, the adhesive film protruding from the adherend 1 was trimmed with a cutter to make the shape of the adhesive film identical to the shape of the adherend 1.

[0169] Next, the second release sheet was peeled off from the laminate, and the exposed surface of the adhesive film after heat pressing was pressed against the dry-polished surface of adherend 2 heated to 120°C on a hot plate, to obtain a structure consisting of adherend 1, the adhesive film after heat pressing, and adherend 2. The obtained structure was heat-treated at 125°C for 1 hour (preheating step), and then heat-treated at 175°C for 2 hours (complete curing step), to completely cure the adhesive film after heat pressing and form a cured product. In this way, a test piece consisting of adherend 1, the cured adhesive film, and adherend 2 was obtained.

[0170] (3) Measurement of shear adhesive strength The test piece obtained in step (2) above was placed on the measurement stage of a bond tester (manufactured by Dage, product name "Bond Tester Series 4000") set to 250°C for 30 seconds, and stress was applied in the direction perpendicular to the adhesive surface (shear direction) at a speed of 200 μm / s from a position 10 μm above the adherend 1 located above the test piece, and the force at which the bond between the cured adhesive film and the dry polished surface of the adherend 2 was broken (shear adhesive strength, N / 5 × 5 mm 2 ) was measured. The average value of the shear adhesive strength for the six test pieces was calculated as a measurement value of one level. The results are shown in Table 2.

[0171] [Table 1]

[0172] [Table 2]

[0173] As can be seen from Table 2, the cured adhesive films produced in the examples had excellent thermal conductivity and excellent shear adhesive strength. Furthermore, the adhesive films produced in the examples (before curing) had good adhesive strength and were not mechanically brittle. [Industrial Applicability]

[0174] The adhesive film according to the present invention can be suitably used, for example, by being interposed between a heat-generating electronic device and a heat-dissipating substrate or heat sink to cool the electronic device. The structure according to the present invention is also useful, for example, as a structure including a heat-generating electronic device and a heat-dissipating substrate or heat sink. [Explanation of symbols]

[0175] 1...Adhesive film 11...Support sheet 12...Release sheet 2...Adhesive film with support sheet 3...Structure 1A...Cured adhesive film 31...First member 32...Second member

Claims

1. A thermally conductive filler (A) having a two-dimensional crystal structure; an epoxy component (B); a curing agent (C); a binder polymer (D); An adhesive film comprising the average particle size of the thermally conductive filler (A) having a two-dimensional crystal structure is 5.0 μm or more and 30 μm or less; the thickness of the thermally conductive filler (A) having a two-dimensional crystal structure is 0.7 nm or more and 500 nm or less; at least one of the epoxy component (B) and the curing agent (C) has a π-conjugated mesogenic skeleton, the content of the thermally conductive filler (A) having a two-dimensional crystal structure in the adhesive film is 5% by mass or more and 60% by mass or less, the epoxy component (B) has a naphthalene skeleton or a biphenyl skeleton as the π-conjugated mesogen skeleton, the curing agent (C) is a phenol-based curing agent having a biphenyl skeleton as the π-conjugated mesogen skeleton, In the absorption spectrum obtained by Raman measurement, the ratio (D / G) of the absorption intensity peak value (I D ) of the D band at a wave number of about 1250 cm −1 to the absorption intensity peak value (I G ) of the G band at a wave number of about 1570 cm −1 is 0.5 or less. An adhesive film characterized by:

2. A thermally conductive filler (A) having a two-dimensional crystal structure; an epoxy component (B) having a π-conjugated mesogenic skeleton; a binder polymer (D); An adhesive film comprising: the average particle size of the thermally conductive filler (A) having a two-dimensional crystal structure is 5.0 μm or more and 30 μm or less; the thickness of the thermally conductive filler (A) having a two-dimensional crystal structure is 0.7 nm or more and 500 nm or less; the content of the thermally conductive filler (A) having a two-dimensional crystal structure in the adhesive film is 5% by mass or more and 60% by mass or less, the epoxy component (B) has a naphthalene skeleton or a biphenyl skeleton as the π-conjugated mesogen skeleton, In the absorption spectrum obtained by Raman measurement, the ratio (D / G) of the absorption intensity peak value (I D ) of the D band at a wave number of about 1250 cm −1 to the absorption intensity peak value (I G ) of the G band at a wave number of about 1570 cm −1 is 0.5 or less. An adhesive film characterized by:

3. An adhesive film as described in claim 1 or 2, characterized in that the binder polymer (D) is an acrylic polymer.

4. The adhesive film according to any one of claims 1 to 3, characterized in that the thermally conductive filler (A) having a two-dimensional crystal structure is graphene.

5. 5. The adhesive film according to claim 1, which is obtained by heat pressing.

6. A method for producing the adhesive film according to claim 1, a thermally conductive filler (A) having a two-dimensional crystal structure and a binder polymer (D) are mixed in a solvent, and then an epoxy component (B), at least one of which has the π-conjugated mesogen skeleton, and a curing agent (C) are further mixed therewith to obtain an adhesive resin composition; The adhesive resin composition thus obtained is formed into a film. A method for producing an adhesive film, comprising:

7. A method for producing the adhesive film according to claim 2, the thermally conductive filler (A) having a two-dimensional crystal structure and the binder polymer (D) are mixed in a solvent, and then the epoxy component (B) having a π-conjugated mesogen skeleton is further mixed therewith to obtain an adhesive resin composition; The adhesive resin composition thus obtained is formed into a film. A method for producing an adhesive film, comprising:

8. 8. The method for producing an adhesive film according to claim 6, wherein the adhesive resin composition is formed into a film and then heat-pressed.

9. The adhesive film according to any one of claims 1 to 4, a support sheet laminated on at least one side of the adhesive film; An adhesive film with a support sheet.

10. A structure in which at least a part of a first member and at least a part of a second member are bonded via a cured product of the adhesive film according to any one of claims 1 to 4.

11. 11. The structure according to claim 10, wherein the first member is a semiconductor element, and the second member is a semiconductor element or a substrate.

12. A method for producing a structure in which at least a part of a first member and at least a part of a second member are bonded via the cured body by bonding at least a part of a first member to at least a part of a second member via the adhesive film described in any one of claims 1 to 4, and then heat-treating the adhesive film to form a cured body.

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